Dec 16 2009

drivers/video: Move dereference after NULL test 

Author: Julia Lawall <julia@diku.dk>

If the NULL test on fbi is needed, then the dereference should be after the
NULL test.

A simplified version of the semantic match that detects this problem is as
follows (http://coccinelle.lip6.fr/):

// 
@match exists@
expression x, E;
identifier fld;
@@

* x->fld
  ... when != \(x = E\|&x\)
* x == NULL
// 

Signed-off-by: Julia Lawall 
Cc: Krzysztof Helt 
Cc: Eric Miao 
Cc: Daniel Mack 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 

---
 drivers/video/pxafb.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
 
diff --git a/drivers/video/pxafb.c b/drivers/video/pxafb.c
index b7e5805..415858b 100644
--- a/drivers/video/pxafb.c
+++ b/drivers/video/pxafb.c
@@ -1221,13 +1221,14 @@ static void setup_smart_timing(struct pxafb_info *fbi,
 static int pxafb_smart_thread(void *arg)
 {
 	struct pxafb_info *fbi = arg;
-	struct pxafb_mach_info *inf = fbi->dev->platform_data;
+	struct pxafb_mach_info *inf;
 
-	if (!fbi || !inf->smart_update) {
+	if (!fbi || !fbi->dev->platform_data->smart_update) {
 		pr_err("%s: not properly initialized, thread terminated\n",
 				__func__);
 		return -EINVAL;
 	}
+	inf = fbi->dev->platform_data;
 
 	pr_debug("%s(): task starting\n", __func__);

qlambert